answer: white fur works as a camouflage against the white snow, allowing polar bears an advantage when hunting for food and hiding from predators
Which answer would represent 0.001 moles?
Answer:
Which answer would represent 0.001 moles?
Hydrogen peroxide with a concentration of 3.0 percent (3.0 g of H2O2 in 100 mL of solution) is sold in drugstores for use as an antiseptic. For a 10.0-mL 3.0 percent H2O2 solution, calculate (a) the oxygen gas produced (in liters) at STP when the compound undergoes complete decomposition and (b) the ratio of the volume of O2 collected to the initial volume of the H2O2 solution.
Answer:
a) 0.099 L
b) 9.9
Explanation:
Now, given the equation for the decomposition of H2O2;
2H2O2(l) ------> 2H2O(l) + O2(g)
Mass of H2O2;
percent w/v concentration = mass/volume * 100
volume = 10.0-mL
percent w/v concentration = 3.0 percent
mass of H2O2 = x
3 = x/ 10 * 100
30 = 100x
x = 30/100
x = 0.3 g of H2O2
Number of moles in 0.3 g of H2O2 = mass/ molar mass
Molar mass of H2O2 = 34.0147 g/mol
Number of moles in 0.3 g of H2O2 = 0.3g/34.0147 g/mol
= 0.0088 moles
From the reaction equation;
2 moles of H2O2 yields 1 mole of oxygen
0.0088 moles of H2O2 = 0.0088 * 1/2 = 0.0044 moles of oxygen
If 1 mole of oxygen occupies 22.4 L
0.0044 moles of oxygen occupies 0.0044 * 22.4/1
= 0.099 L
b) initial volume of the H2O2 solution = 10 * 10-3 L
Hence, ratio of the volume of O2 collected to the initial volume of the H2O2 solution = 0.099 L/10 * 10-3 L = 9.9
Which one is not an ore of copper
1 Azurite
2 Malachite
3 Haematite
4 Chalcopyrite